Vaccines are weekend forms of disease causing microorganisms which are given to patients to prevent diseases. after the vaccine is administered what response to the vaccine is triggered in the body?
a. secretion of antigens by lymphocytes
b. absorption of histamine throughout the body
c. production of temporary resistance to the disease
d. production of antibodies providing active immunity

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.